Oil and gas hydrocarbons are naturally occurring in some subterranean formations. A subterranean formation containing oil or gas is sometimes referred to as a reservoir. A reservoir may be located under land or off shore. Reservoirs are typically located in the range of a few hundred feet (shallow reservoirs) to a few tens of thousands of feet (ultra-deep reservoirs).
In order to produce hydrocarbons, a wellbore is drilled through a hydrocarbon-bearing zone in a reservoir. In a cased-hole wellbore or portion thereof, a casing is placed, and typically cemented, into the wellbore providing a tubular wall between the zone and the interior of the cased wellbore. A tubing string can then be run in and out of the casing. Similarly, tubing string can be run in an uncased wellbore or section of wellbore. As used herein, “tubing string” refers to a series of connected pipe sections, joints, screens, blanks, cross-over tools, downhole tools and the like, inserted into a wellbore, whether used for drilling, work-over, production, injection, completion, or other processes. Further, in many cases a tool can be run on a wireline or coiled tubing instead of a tubing string, as those of skill in the art will recognize. A wellbore can be or include vertical, deviated, and horizontal portions, and can be straight, curved, or branched.
During wellbore operations, it is typical to “hang” a liner onto a casing such that the liner supports an extended string of tubular below it. Expandable liner hangers are generally used to secure the liner within a previously set casing or liner string. Expandable liner hangers are “set” by expanding the liner hanger radially outward into gripping and sealing contact with the casing or liner string. For example, expandable liner hangers can be expanded by use of hydraulic pressure to drive an expanding cone, wedge, or “pig,” through the liner hanger. Other methods can be used, such as mechanical swaging, explosive expansion, memory metal expansion, swellable material expansion, electromagnetic force-driven expansion, etc.
The expansion process is typically performed by means of a setting tool used to convey the liner hanger into the wellbore. The setting tool is interconnected between a work string (e.g., a tubular string made up of drill pipe or other segmented or continuous tubular elements) and the liner hanger. The setting tool expands the liner hanger into gripping and sealing engagement with the casing.
If the liner hanger is expanded using hydraulic pressure, the setting tool is generally used to control communication of fluid pressure and flow, such as between various portions of the liner hanger expansion mechanism and between the work string and the liner. The setting tool may also be used to control release of the work string from the liner hanger, for example, after expansion, in emergency situations, or after unsuccessful setting attempts. It is desirable to maintain a low equivalent circulating density (ECD), to minimize wall thickness of the setting tool and liner hanger assembly, so that the assembly can be conveyed rapidly into the well.
As can be appreciated, the expanded liner hanger must support the substantial weight of the attached tubing string below. For deep and extra-deep wells, subsea wells, etc., the tubing string places substantial axial load on the hanging mechanism grippingly engaging the liner hanger to the casing. There is a need for methods and apparatus providing an expandable liner hanger having a gripping mechanism and sealing mechanism capable of supporting the substantial axial loads imparted by today's longer and heavier liner strings.
It should be understood by those skilled in the art that the use of directional terms such as above, below, upper, lower, upward, downward and the like are used in relation to the illustrative embodiments as they are depicted in the figures, the upward direction being toward the top of the corresponding figure and the downward direction being toward the bottom of the corresponding figure. Where this is not the case and a term is being used to indicate a required orientation, the Specification will state or make such clear.